Electricity: electrical systems and devices – Electrolytic systems or devices – Solid electrolytic capacitor
Reexamination Certificate
2000-02-16
2001-11-20
Reichard, Dean A. (Department: 2831)
Electricity: electrical systems and devices
Electrolytic systems or devices
Solid electrolytic capacitor
C361S528000, C361S437000, C361S508000, C029S025030, C029S516000
Reexamination Certificate
active
06320742
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a solid electrolytic capacitor having a solid electrolyte layer, and a method of manufacturing the same.
BACKGROUND OF THE INVENTION
A conventional solid electrolytic capacitor of this type is structured as shown in FIG.
7
. In
FIG. 7
, the solid electrolytic capacitor comprises a valve metal
5
having an anode lead-out part
2
and a capacitor element part
3
, a dielectric oxide layer disposed on the valve metal, a conductive high polymer layer disposed on the dielectric oxide layer, a conductor layer disposed on the conductive high polymer layer, an anode terminal
6
, a cathode terminal
7
, and an external resin
8
. The valve metal
5
has a roughened surface or porous layer processed by etching. The anode lead-out part
2
and capacitor element part
3
are separated from each other by a resist material
1
disposed on the surface of the valve metal
5
. The dielectric oxide layer is formed by anodic oxidation. The anode terminal
6
is electrically connected to the anode lead-out part
2
. The cathode terminal
7
is electrically connected to the conductor layer. The external resin
8
is formed by molding to cover the entire capacitor element.
Herein, the conductive high polymer layer is formed either by a method of forming by electrolytic oxidation polymerization by the use of monomer, or by a method of forming to chemical oxidation polymerization. The electrolytic oxidation polymerization is a method of forming a conductive high polymer layer on the surface of a manganese dioxide layer preliminarily formed on a dielectric oxide layer. The chemical oxidation polymerization is a method of forming a conductive high polymer layer directly on the surface of a dielectric oxide layer.
In the solid electrolytic capacitor shown in
FIG. 7
, however, the valve metal having the roughened layer or porous layer is divided into the anode lead-out part
2
and capacitor element part
3
by means of the resist material
1
, but the conductive high polymer layer contacts with the anode lead-out part
2
through the gap
4
of the roughened layer or porous layer, and defective insulation may occur, or insulation breakdown may take place. Accordingly, it has been proposed to broaden the width of the resist material
1
, or use a material having a high adhesion to the valve metal. In such proposals, too, it was difficult to obtain stable effects always in numerous production lots, and achieve a stable and low defective rate of insulation. It was also disadvantageous from the viewpoint of cost.
It is hence an object of the invention to present a solid electrolytic capacitor which can be manufactured in a relatively easy method, and is capable of preventing defective insulation due to conductive high polymer layer reaching up to the anode lead-out portion, and preventing occurrence of insulation breakdown, while maintaining the conventional excellent productivity.
SUMMARY OF THE INVENTION
The solid electrolytic capacitor of the invention comprises:
an anode electrode having a capacitor element part, forbidden band, and an anode lead-out part,
in which the forbidden band has a boundary portion placed between the capacitor element part and anode lead-out part so as to separate the capacitor element part and anode lead-out part,
a dielectric oxide layer disposed on the capacitor element part,
a conductive high polymer layer disposed above the dielectric oxide layer,
a conductor layer disposed above the conductive high polymer layer,
an anode terminal connected electrically to the anode lead-out part, and
a cathode terminal connected electrically to the conductor layer.
Preferably, the anode electrode has at least one undulated layer of roughened layer and porous layer.
Preferably, the anode electrode has a valve metal forming at least one layer of roughened layer and porous layer.
Preferably, the solid electrolytic capacitor further has a resist material disposed on the forbidden band.
The manufacturing method of solid electrolytic capacitor of the invention comprises:
(a) a step of feeding an anode electrode,
(b) a step of forming a forbidden band in the anode electrode in order to form a boundary portion between the capacitor element part and anode lead-out part,
(c) a step of forming a dielectric oxide layer on the capacitor element part,
(d) a step of forming a conductive high polymer layer above the dielectric oxide layer,
(e) a step of forming a conductor layer above the conductive high polymer layer,
(f) a step of connecting an anode terminal electrically to the anode lead-out part, and
(g) a step of connecting a cathode terminal electrically to the conductor layer.
Preferably, the step of feeding the anode electrode includes a step of forming at least one undulated layer of roughened layer and porous layer on the surface of the anode electrode.
Preferably, the anode electrode has a valve metal, and the step of feeding the anode electrode includes a step of forming at least one undulated layer of roughened layer and porous layer on the surface of the anode electrode.
Preferably, this method includes a step of disposing a resist material on the forbidden band.
In this constitution, a solid electrolytic capacitor having equivalent or superior basic electric performance as compared with the conventional product can be obtained in a relatively simple manufacturing method. It further prevents defective insulation caused by the conductive high polymer layer reaching the anode lead-out part. Occurrence of insulation breakdown is prevented. Moreover, the conventional productivity is not sacrificed. The solid electrolytic capacitor having such effects and its manufacturing method are obtained.
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patent: 4110815 (1978-08-01), Frade et al.
patent: 4785380 (1988-11-01), Harakawa et al.
patent: 4805074 (1989-02-01), Harakawa et al.
patent: 4934033 (1990-06-01), Harakawa et al.
patent: 5428500 (1995-06-01), Nishiyama et al.
patent: 5432029 (1995-07-01), Mitate et al.
patent: 5443602 (1995-08-01), Kejha
patent: 5473503 (1995-12-01), Sakata et al.
patent: 59-23889 (1984-02-01), None
patent: 60-137923 (1985-07-01), None
patent: 63-158829 (1988-07-01), None
patent: 62-165313 (1989-07-01), None
Kobatake Yasuhiro
Shimada Hiroshi
Wada Tomohide
Ha Nguyen T
Matsushita Electric - Industrial Co., Ltd.
Ratner & Prestia, PC
Reichard Dean A.
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